The invention relates to an installation for treating, in particular coating, articles, especially vehicle bodies, having
a) at least one bath, in which a treatment liquid, in particular a paint, is located, in which the articles are intended to be immersed;
b) a conveying means, with which the articles may be conveyed through the installation in a continuous or intermittent translational movement;
c) a plurality of immersion means, which are connected with the conveying means, each carry one article and are in a position to immerse this article in the bath.
An installation of this type is described in DE 196 41 048 C2. The conveying means therein consists of guide rails, in which there run drive means, not described in any more detail; examples of these drive means are chains, hauling ropes, geared rods or the like. A plurality of mounting frameworks for the bodies to be coated are connected with the drive means at regular intervals and are displaced translationally thereby. The translational movements of all the bodies to be coated are in this way compulsorily coupled together. The bodies are immersed in and extracted from the treatment fluid by rotary motion of the mounting frameworks about an axis, which extends horizontally and perpendicularly to the direction of the translational movement. The forces which rotate the mounting frameworks are derived from the translational movement by a kind of cam/crank means, such that the instantaneous angle of rotation of the mounting frameworks always clearly results from the position of the mounting framework in the direction of translation.
A disadvantage of this known installation is its lack of flexibility: as already mentioned, all the articles to be coated can only move jointly in the transport direction. Thus, all the articles in the installation have to pass through the baths in the same way, with the same kinematics and at the same speed. This frequently does not fulfil the requirements of a modern installation, in which successive articles need to be treated in different ways.
The object of the present invention is so to design an installation of the above-mentioned type that it allows altogether more flexible treatment of the individual articles.
This object is achieved according to the invention in that
d) the conveying means comprises a plurality of independent transport carriages, which run in guided manner on running surfaces and each comprise a separate drive for translational movement and a drive operating independently thereof for the immersion movement.
According to the invention, therefore, the rigid coupling present in the prior art between the various mounting frameworks is abandoned and replaced by a plurality of individual transport carriages, which may basically move independently of one another. Each of these transport carriages has its own drive for translational movement. The speeds of the individual transport carriages may thus be independently selected; the intervals between successive transport carriages may be enlarged or reduced. It is additionally possible to guide the immersion movement of the articles independently of the translation movement, since a separate drive is provided for this immersion movement. Thus, for instance a bath may be missed out, simply by not actuating the drive of the carriage for the immersion movement at the appropriate point in the transport path. It is also possible firstly to miss out a bath and then to perform the article immersion process in a backwards movement. This immersion direction may be more favourable than an immersion movement in the forwards direction in particular in the case of bodies which have doors which come open or the like. Moreover, each article to be coated may be individually subjected to a swinging movement within the bath. Articles comprising cavities, like vehicle bodies, may be completely emptied above the respective bath by suitable movements, such that as little as possible of the paint is entrained out of the bath. The speed of the translational movement may be reduced above and in the baths, so resulting in long residence times therein, while the speed of translation between the baths may be increased. Loading and delivery of the articles to be treated may, on the other hand, be performed at a standstill. Altogether, the shortest possible bath lengths may be achieved in this way, such that the space requirement of the overall system is reduced.
In the case of a fault, individual transport carriages may easily be removed from the installation. The risk of bath contamination is reduced in that all conveying system components may be arranged laterally of the baths.
An advantageous further development of the installation according to the invention is distinguished in that at least one vertically oriented transport flange extends parallel to a running surface and in that the drive for the translational movement of each transport carriage comprises a pressure roll drive, which comprises at least two pressure rolls running under pressure on opposing side faces of the transport flange, at least one of which pressure rolls is driven. Drive of the transport carriages for the translational movement thus proceeds not via the running wheels themselves but rather via the above-mentioned, separate pressure roll drive, which interacts with the stationary transport flange. This simplifies control of the transport carriages on their path through the installation. Moreover, good acceleration and deceleration may be achieved with such a drive.
The running wheels of the transport carriages may be rotated about a vertical axis by means of a pivoted bolster. In this embodiment of the invention, the running wheels are thus steerable, which reduces wear and precision requirements for instance in comparison with normal rail running wheels. In particular, by appropriately rotating the pivoted bolsters of the running wheels about the perpendicular axis, the transport carriages may also be moved sideways out of the conveying line, perpendicularly to their longitudinal extension.
At least two wheels of each transport carriage are preferably provided with a leading guide member, which encompasses a profile of the associated running surface and is connected with the pivoted bolster. The transport carriages are conveyed through the installation by these guide members, wherein cornering is straightforwardly possible. The other two wheels of the transport carriages do not need to be guided; they may take the form of simple follower wheels.
The precise configuration of the mounting and guidance of the running wheels and the design of the running wheels themselves may be based on the constructions described in DE 44 27 191 C2, DE 197 44 446 A1 and also DE 199 34 746 A1.
The immersion means may be a rotary means, which immerses the articles in the treatment liquid by rotation about an approximately horizontal axis. The present invention may thus also be used in the case of immersion kinematics as put into practice in the above-described DE 196 41 048 C2.
An exemplary embodiment of the invention is explained in more detail below with reference to the drawings, in which
FIG. 1: shows a perspective portion of a dip-coating installation for vehicle bodies;
FIG. 2: shows a section through the installation of FIG. 1 perpendicularly to the direction of movement of the vehicle bodies, viewed form the bottom right;
FIG. 3: is a side view of the portion of the coating installation of FIG. 1;
FIG. 4: is a side view of a transport carriage used in the coating installation, having a vehicle body attached thereto;
FIG. 5: is a perspective view of the transport carriage plus vehicle body of FIG. 4;
FIG. 6: shows an enlarged detail taken from the area of the circle labelled with letter A in FIG. 2;
FIG. 7: shows an enlarged detail from the area of the circle labelled with letter B in FIG. 2.